1. Field of the Invention
The present invention relates to an ink jet recording apparatus, particularly an ink jet recording apparatus having a recovery device of an ink jet recording head.
2. Related Background Art
U.S. Pat. No. 4,692,778 shows one of the conventional ink jet recording apparatuses having, for example a full-line type ink jet recording head. This ink jet recording apparatus as shown in FIG. 1, comprises an ink jet recording head 1, recording medium conveying mechanism having a platen 15 provided opposite to the ink jet recording head 1 and recording medium conveying rollers 16a and 16b, a head recovery device 2 provided on the same side of the ink jet recording head 1 with respect to the recording medium conveying mechanism and a controller 17.
In such an ink jet recording apparatus, during recording the recording medium is fed from the recording medium conveying roller 16a to the platen 15 in the direction of an arrow A as shown in FIG. 2A and recording is performed by discharging ink as droplets by utilizing thermal energy from the ink jet recording head 1 having elements for generating thermal energy utilized for discharging ink in response to a predetermined recording signal. Drawing of air bubbles generated upon application of thermal energy with respect to an ink discharge mechanism of an ink jet recording head is disclosed in U.S. Pat. No. 4,723,129 and driving for ink discharge is disclosed in U.S. Pat. No. 4,463,359. In case of unstable discharge or non-discharge of ink which can cause inferior recorded images during recording, the ink jet recording head is recovered. This recovery operation is performed by the head recovery device 2 as shown in FIGS. 2A, 2B and 2C. First, the ink jet recording head 1 disposed at a recording position is retracted in the direction of an arrow a as shown in FIG. 2A and then the head recovery device 2 is moved in the direction b as shown in FIG. 2B until it is opposite to the ink jet recording head 1. Finally the ink jet recording head 1 is moved in the direction c as shown in FIG. 2C to contact the head recovery device 2, thus performing the recovery operation.
During non-recording where a recording signal is not applied more than a predetermined time period, as similary during the recovery operation, in order to protect the ink jet recording head 1 the head recovery device 2 moves to a position opposite to the ink jet recording head 1, and contacts the ink jet recording head 1 for capping treatment.
On the other hand, in case of an ink jet recording apparatus in which the recording medium is conveyed by a conveying belt and recording is performed by the full-line type recording head in which discharge ports are arranged over a recordable area of the recording medium and in a direction across the conveying direction of the recording medium, the recovery operation and capping operation have been performed by a method similar to the above mentioned method.
However, when the recording head is recovered in the above stated conventional apparatus, both the ink jet recording head and the recovery device have to move complicatedly as shown in FIGS. 2A to 2C. Accordingly there are problems such as that a long time is required to recover the recording head, that complicated and highly accurate constitution is required to perform recovery and a large space for providing the recording head and the head recovery device and a large space in which both the head and the recovery device can move upon a recovery operation is required.
In addition, since the recovery operation is complicated, it is difficult to perform a delicate recovery operation such as ink discharge of a few pulses in order to prevent nozzles unused for a predetermined time period during recording from clogging caused by evaporation of ink solvent and from poor record such as dot breakage.
Furthermore, it costs high to constitute the mechanism for complicatedly and accurately moving both the ink jet recording head and the recovery device.